The application of organic semiconductors to photoelectric conversion devices such as a photovoltaics, a light emitting element, and a photosensor is being expected. Using an organic semiconductor as a forming material of an active layer of a photovoltaics and the like makes it possible to employ an inexpensive coating method for forming the active layer and the like, and thus enables a great reduction of a formation cost of the active layer and the like. Because of these points, an organic photovoltaics and an organic/inorganic hybrid photovoltaics which use an organic semiconductor are expected as a next-generation photovoltaics that cost low and are harmless.
Cells forming a photovoltaic module each have a structure in which an active layer is sandwiched by a transparent electrode and a counter electrode. A transparent electrode on a practical level does not have sufficient conductivity, and accordingly efficiency for extracting generated electric charges deteriorates as a cell area is increased. As a forming material of the transparent electrode, a conductive metal oxide, a conductive polymer, a carbon material, or the like is used, and further, a material in which a metal nanowire or the like is compounded with any of these is used. In a photovoltaic module, generally, a plurality of strip-shaped cells are arranged and the plural cells are connected in series.
A photovoltaic module having a plurality of cells is formed by the following method, for instance. Transparent electrodes of the respective cells are formed on a transparent substrate. An organic active layer is formed on the whole surface of the plural transparent electrodes by coating. Part of the organic active layer is scribed, whereby grooves from which the transparent electrodes are exposed are formed. Counter electrodes are formed on the organic active layer having the scribe grooves so as to correspond to the respective cells. At this time, in the scribe groove, the counter electrode of the adjacent cell is filled, so that the counter electrode of the adjacent cell is electrically connected with the transparent electrode exposed in the scribe groove.
The scribing of the organic active layer is executed by mechanical scribing using a cutting tool, for instance. In a case where a conductive metal oxide is used as the transparent electrode, a hard transparent conductive oxide layer exists under the soft organic active layer, and thus at the time of the mechanical scribing of the organic active layer, the organic active layer is likely to remain on the conductive metal oxide. The organic active layer, if remaining on the conductive metal oxide, increases electrical resistance between the transparent electrode and the counter electrode of the adjacent cell, resulting in deterioration of power conversion efficiency. Increasing a scribing pressure so as to prevent the organic active layer from remaining is likely to cause a crack or the like in the transparent conductive oxide layer. In a case where a conductive polymer is used as the transparent electrode, the transparent electrode has the same softness as that of the organic active layer, which makes it difficult to selectively scribe the organic active layer so that the conductive polymer remains without the organic active layer remaining.
The above circumstances have given rise to a demand for an art to improve electrical connectivity between the adjacent cells (photoelectric conversion parts) by achieving both the prevention of the organic active layer from remaining on the transparent electrodes and the prevention of breakage of the transparent electrodes at the time of the mechanical scribing of the organic active layer.